When the retired Queensland schoolteacher Phoebe Morwood-Oldham started an online petition following her son’s suicide in April 2013, she could not have known that her insistence on asking hard questions of one of the world’s largest pharmaceutical companies would lead to an Australian-first finding by a state coroner.

On Thursday in Brisbane magistrates court, coroner John Hutton found that a commonly prescribed drug named Champix – manufactured by Pfizer and sold internationally under the name Chantix – contributed to the death of a 22-year-old Brisbane man, Timothy John, who died by suicide soon after he began taking a medication that he had hoped would cut his smoking habit from eight cigarettes a day down to zero.

Timothy John with his mother, Phoebe Morwood-Oldham.

For Morwood-Oldham, the finding was a satisfying outcome for a lengthy process that began with a Change.org petition that she started four years ago, which asked for on-the-box warning labels on Champix packaging. It has been signed by 49,000 people. “His death still hurts so deep,” she wrote at the top of the petition. “After taking the anti-smoking drug marketed as ‘Champix’ for just 8 days, my beautiful boy hung himself. But despite reports of 25 suicides linked to Champix in seven years – there still aren’t proper side-effect warnings.”

Every Sunday for four years Morwood-Oldham and her older son, Peter, have visited Timothy’s grave at Cleveland cemetery. The weekly routine involves the laying of lillies and turning their minds toward a young man who was, as his headstone says, “much wanted and loved”. Morwood-Oldham tells Guardian Australia that Timothy’s death “was so sudden” and it affected her deeply.

“I lost the person I love the most in the world, in eight days. I never expected it.”

Talking about Timothy, Morwood-Oldham warns that her emotions are “all over the place”. He is never far from his mother’s mind, nor her gaze: when she opens her laptop to share some photographs, there he is, her screensaver. A cute, blond boy aged six, aiming a cheeky smile at the lens.

Timothy had suffered mental health issues, something his mother speaks of in terms of grades out of 10. He had for a time been a 4/10, then, after cognitive behaviour therapy, he was back to 9/10.

“How did he go from a 9/10 to a 1/10 in eight days on Champix?” she said. “The autopsy showed there were no alcohol or drugs in his system other than Champix and Ibuprofen.”

The inquest heard that, on a drive back from the Gold Coast just hours before his death, Timothy asked, “Mum, do you think I should give up the Champix? It’s making me feel strange.” Morwood-Oldham told the original two-day inquest in November last year: “I said to him, ‘Timothy, if it’s helping you to give up smoking maybe you keep it up’.” She had not been part of the consultations with her son’s GP when he was prescribed the drug and the Champix packaging did not contain warnings for any potential adverse effects.

The night before, his behaviour had been disturbing. Morwood-Oldham found Timothy sitting on the floor with an electric chainsaw plugged in, talking about people coming to get him. She stayed with him all night and made sure he was safe. But the next day he left a taped message on a voice recorder for his mother on the kitchen bench:

Mum, I love you with all my heart. Peter, you’re the best brother I could ask for. I know it doesn’t make sense right now but it’s for the best, trust me. I’m losing my mind. I’m going crazy. I love you both.

According to Morwood-Oldham, he had never expressed suicide ideation before.

Now Hutton’s findings are a kind of vindication. “I find that Champix contributed to Timothy’s death,” the coroner said. “However, I am unable to determine the level of contribution that Champix had on Timothy’s death due to his pre-existing mental health condition.”

I lost the person I love the most in the world, in eight days.

Phoebe Morwood-Oldham

In addition, the coroner found that “certain aspects of the product labelling and instructions provided with Champix are inadequate and some improvements can be made”.

Hutton noted that the drug “does in fact increase the risk of suicide in patients such as Timothy, with a history of a psychiatric disorder, compared to people attempting to quit smoking without a medical aid”. Accordingly, the coroner stated that “it is therefore important to closely monitor people with a history of psychiatric disorders, such as Timothy, whilst they are taking Champix”.

In the US, Pfizer made out-of-court settlements to 2,700 complainants totalling US$273m after a 2013 class action that claimed the drug Chantix raised the risk of suicide. In 2014, there was a strengthening of the “black box” warning on the drug packaging alerting users to serious side effects, which the FDA has since removed.

In Australia, Champix was approved by the Therapeutic Goods Administration as “an aid to smoking cessation in adults over the age of 18 years” on 15 February 2007. Data provided by the TGA to Guardian Australia show that 1,717,066 prescriptions for Champix were dispensed nationwide in the five years between 2011-2012 and 2015-16. The drug has been listed on the Pharmaceutical Benefits Scheme since 1 January 2008.

Up to May 2010, according to the TGA, there were reports of 206 suicide-related events in people taking varenicline – the chemical name for the drug, which assists with smoking cessation by blocking nicotine receptors in the brain, reducing cravings and decreasing the pleasurable effects of tobacco products. There are no external or internal warnings on the packaging in Australia.

When Hutton asked Pfizer’s legal counsel why there was no consumer medicine information leaflet included with in the packaging, he was told: “It’s to ensure the currency of the document, your honour. It’s available in electronic form.” The coroner interrupted: “When I get my drugs I don’t go to the computer and start looking up the drugs. I rely on the manufacturer to put the updated version of the warnings in the box.”

It was only after her son’s death that Morwood-Oldham went to her pharmacist and asked for a print-out of the consumer medicine information relating to Champix. The most recent version of this document, updated by Pfizer in March 2017, notes that “Your family and friends should be asked to monitor any changes in your behaviour, thinking or mood that are not typical for you e.g. if you develop suicidal thoughts or actions, anxiety, panic, aggression, anger, mania, abnormal sensations, hallucinations, paranoia or confusion. Discuss with your doctor the benefits and risks of taking Champix to decide if it is right for you.”

Other state coroners have examined suicides where Champix was present, such as the Victorian state coroner finding that a 36 year-old Frankston man, Benjamin David Johnston, died by suicide in February 2015. In that case, the coroner found that “the evidence supports that his death was an adverse reaction to varenicline”. In May 2011, a Tasmanian coroner found it was “impossible to say” whether Champix was a direct causal link to the suicide of a father of three, “Mr P”, who died by a self-inflicted shotgun wound at his home in November 2009. At Timothy John’s inquest last year, two sets of parents of young men who had killed themselves while taking Champix attended, having travelled from WA for the hearing. None of these cases was subject to inquests.

In a 24-page submission to the inquest dated 31 July 2017, and seen by Guardian Australia, the American pharmaceutical company gave a forthright, pre-emptive rejection of coroner Hutton’s findings. The document begins: “At the outset, it is submitted that a) there is a robust body of scientific evidence which demonstrates that the risk of neuropsychiatric adverse events with varenicline does not differ significantly when compared to placebo, and b) this body of scientific evidence outweighs likely coincidence in a single case.”

In addition to asserting that “there is no reliable evidence to allow the coroner to reach such a conclusion” that Champix was a present factor in Timothy John’s death, Pfizer noted – in bold type – that “Mr John’s behaviour at and around the time of his tragic suicide was consistent with prior behaviours he had demonstrated and the prescription of Champix was merely coincidental”. In the same document, the deceased was described as “a very troubled young man with a lot of anger and interpersonal problems”.

Timothy John as a child.

Page 15 of Pfizer’s submission to the coronial inquest referred to a statement from the TGA, which noted that 2.8 million prescriptions for the drug were filled nationwide between 2008 and 2014. A statement attributed to the Therapeutic Goods Administration within Pfizer’s submission read: “The TGA is of the view that there is currently insufficient evidence to date that provides a direct causal connection between Champix and serious neuropsychiatric adverse events and that there are a number of confounding factors which may have contributed to these adverse events.”

When Guardian Australia queried the TGA as to whether it had made any statements or submissions in relation to the Timothy John inquest, a spokeswoman for the federal health department replied via email: “The TGA was not involved in any inquest and provided no public statements on this issue.”

Currently, Victoria is the only state in Australia wherein toxicology screening for the presence of varenicline is undertaken in all suicides and suspected suicides. This recommendation was made by the Victorian state coroner, Jacqui Hawkins, in December 2015 as part of the findings into the death of Benjamin David Johnston.

Now as a result of the Timothy John inquest, Hutton recommends that all state and territory forensic pathology services follow Victoria’s lead and routinely screen for the drug to create a national data set that “may assist in terms of a closer examination of the extent that varenicline can be linked to suicide in the future”. In its submission to the inquest dated 31 July 2017, the Champix manufacturer wrote: “Whilst Pfizer has no objection to such a course it points out that such data will only indicate varenicline as a present factor … Thus, undertaking testing for varenicline where there are other confounding factors may be of little if any value.”

Outside the Brisbane magistrates court, moments after hearing the coroner’s findings, Morwood-Oldham’s mood was buoyant. “I never thought that would happen,” she said. “How are you going to fight a corporation that’s got so many resources?

“My motivation is to save other people from going through what I’ve gone through. Nothing’s going to bring my son back. All I can do is try and help somebody else – and I’ve achieved it. I’m just so pleased.”